The therapeutic potentials and mechanism of single-pulsed electromagnetic field on disuse osteoporosis

Abstract

Osteoporosis is one of the world’s most prevalent bone diseases Disuse the lack of skeletal mechanical loading resulting from disease such as spinal cord injury stroke or muscular dystrophies is one of the reasons that leads to secondary osteoporosis Single-pulsed electromagnetic field (SPEMF) was shown to increase osteogenic differentiation of stem cells and accelerate new bone formation in mice Here we investigate the therapeutic potential of SPEMF on disuse osteoporosis and its underlying molecular mechanism Mice were divided into four groups (1) healthy (INT) mice (2) INT+SPEMF (3) denervation-induced osteopenic (IOP) mice and (4) IOP +SPEMF The results showed that SPEMF reversed bone loss in IOP mice in 6 weeks The percent bone volume (BV/TV) and trabecular number (Tb N) of IOP+SPEMF group were significantly increased than IOP mice on week 6-8 Moreover the microarchitecture of IOP+SPEMF group was restored to INT levels in 8 weeks For osteoblastic cells both short-term (SS; the first 5 days) and long-term (SL) SPEMF treatment increased the mineralization while alkaline phosphatase (ALP) activity was increased on the first 5 days of treatment SS treatment increased gene expression of Wnt1/3a/10b Fzd9 ALP and Bmp-2 SPEMF inhibited sclerostin after 5 days of treatment and that inhibition was more significant by SL treatment SL SPEMF increased the expression of parathyroid hormone-related protein (PTHrP) but decreased the expression of Sost gene which encodes sclerostin Besides by microarray hybridization we also found SPEMF-activated gap junctional signaling For osteoclastic cells SPEMF stimulation did not alter the expression of osteoclastic genes Acp5 Nfatc1 and Ctsk but down-regulated Mmp9 SPEMF did not significantly decrease the osteoclastic cells Together SPEMF restored bone mass of disuse osteopenic mice and may contribute to the exert of osteogenesis by osteoblasts The study validate the therapeutic potential of SPEMF in disuse osteoporosis and provide a new insight for clinical applications

Date of Award	2015 Nov 10
Original language	English
Supervisor	Kuo-An Lai (Supervisor)